AirHint found the following cheapest return flights from London (LON) to Bangkok (DMK) in September 2025 (see full year).

Return flights

30 Sep - 14 Oct	Pegasus Airlines
26 Sep - 19 Oct	AJet
18 Sep - 22 Sep	AJet
26 Sep - 12 Oct	AJet
19 Sep - 10 Oct	AJet
25 Sep - 19 Oct	Pegasus Airlines
19 Sep - 02 Oct	Wizz Air UK
25 Sep - 12 Oct	Pegasus Airlines
24 Sep - 08 Oct	Wizz Air UK
20 Sep - 22 Sep	Wizz Air UK
22 Sep - 02 Oct	Wizz Air UK
26 Sep - 06 Oct	AJet
22 Sep - 29 Sep	Wizz Air UK
21 Sep - 25 Sep	Wizz Air UK
21 Sep - 29 Sep	Pegasus Airlines
19 Sep - 29 Sep	Pegasus Airlines
18 Sep - 30 Sep	Pegasus Airlines
25 Sep - 29 Sep	Pegasus Airlines
25 Sep - 30 Sep	Pegasus Airlines
21 Sep - 30 Sep	Pegasus Airlines

Also check the deals for one-way flights from London to Bangkok in September.

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from London to Bangkok in September from $552

Return flights